Replacement of animals in cancer drug development by using 3D in vitro functional assays for increased predictive power

Cancer therapeutics have a higher attrition rate comparatively to many other therapeutic areas. Preclinical testing of potential candidates typically involves applying the compound to 2D tumour cell culture systems and assessing the impact of the compound on cell proliferation. The best candidates are then assessed in a relevant animal model. The inability of 2D in vitro assays to accurately predict the in vivo response is one of the contributing factors to the high attrition rate of cancer therapeutics. This is likely due to the relative simplicity of the 2D cell culture, which does not accurately replicate the complexity of the tumour in the body.

Why we funded it

This Project Grant aims to develop 3D in vitro functional assays as a replacement for animals required in the preclinical testing stage of cancer drug development.

The Cancer Therapeutics department of the Institute of Cancer Research requires approximately 2000 mice per year for in vivo testing of molecularly targeted drug discovery projects. Dr Chesler estimates using the 3D assays in preclinical testing could reduce the number of compounds progressing to in vivo testing, reducing the numbers of animals required by 400 a year. To exemplify the assays, this project grant focusses on malignant brain tumours, which also use transgenic murine models to better replicate the disease. Transgenic models require breeding colonies to sustain the necessary population needed for studies. Using the in vitro assay as a replacement for one such study requiring a transgenic model could further replace up to 750 to 1000 animals per year.

Research methods

3D culture systems, compared to 2D cultures systems, more faithfully reproduce the in vivo tumour microenvironment in terms of gene expression profiles, signalling pathway activation, cell-cell interactions, matrix deposition, and nutrient and oxygen gradients. In initial experiments, Dr Chesler and colleagues have demonstrated 40 different cancer cell lines were able to form 3D spheroids spontaneously in their multicellular tumour culture system. In this project grant, functional assays, which are both reproducible and quantifiable, will be developed for tumour growth, invasion and angiogenic potential for a panel of 3D cancer spheroids. Once optimised, the response of the cells to inhibitors will be compared to results previously obtained in both 2D and in vivo systems. The developed assays will also be modifiable for a high-throughput format, allowing screening of novel cancer drugs in a more in vivo like environment.